Method for protecting skin from hazardous chemicals

ABSTRACT

Improved polymer barrier for protective garments for personal protection against hazardous chemicals (e.g. epoxy products, organic solvents and pesticides) and a rational method of selecting polymer membranes with optimal permeation resistance against hazardous chemicals. As an excellent barrier against epoxy products and solvents a protective garment contains a membrane of a vinyl alcoholethylene copolymer. Said copolymer was selected by the invented optimization method (the three dimensional solubility parameter concept).

This is a divisional of U.S. application Ser. No. 785,094, filed Oct. 4,1985, which was a continuation of U.S. application Ser. No. 557,159,filed Nov. 9, 1983, now abandoned.

FIELD OF THE INVENTION

The present invention relates to protective garments or clothings forthe protection against the influence of chemicals.

BACKGROUND OF THE INVENTION

There is a great need for protective garments with a low permeability(i.e. a long breakthrough time and a low permeation rate) for certainchemical compounds or mixtures of compounds. The polymer membranes usedin protective garments (e.g. gloves, coverall suits, hoods, boots, etc.)for use in a work environment or in the home must protect againstchemical compounds or mixtures thereof which are hazarduos to thehealth, such as solvents, paints, varnishes, glues, cleaning agents,degreasing agents, drilling fluids, or epoxy materials. Regardingprotective clothing against hazardous chemicals in the work environmentor the home, the main concern has previously been to obtain chemicalresistance of the clothing, i.e. non-degradability. During the latestyears strong concern about the permeability of protective clothingagainst chemicals has developed. Permeation studies have surprisinglyshown that the breakthrough time is often less than half an hour,sometimes only a few minutes. The studies have also shown that thebreakthrough time and the permeation rate is to a great extent dependenton the combination of the hazardous substances and the materials forprotective clothing. In view of the foregoing, it is quite obvious thata great need exists for protective garments featuring polymer membraneswithout the aforementioned disadvantage. Unfortunately, no other methodof selecting suitable combinations than the method of trial and errorhas been proposed. Epoxy materials and many solvents are particularlyimportant in this context due to their toxic effects and allergenicproperties on mammalian skin, in particular human skin.

SUMMARY OF THE INVENTION

The present invention relates to improved protective garments forprotection against chemicals, in particular epoxy materials, and to arational method of selecting polymer membranes with optimal permeationresistance against hazardous chemicals.

In connection with the research which led to the present invention theapplicant has found that commonly used membrane materials (such aspolyethylene, various rubbers, neoprene, silicone rubbers, etc.) haveinsufficient barrier properties with respect to e.g. epoxy materials, inthat they have breakthrough times of an hour or less. Some of thesemembrane materials have even been suggested or recommended as materialsfor proctective garments by manufacturers of epoxy. Applicant hasfurther found that the three-dimensional solubility parameter systempioneered and described by C. M. Hansen (cf. ref. 1, 2, 3 and 4) maysuitably be used as a guide for the rational selection of suitablebarrier membrane materials for protection garments.

The three solubility parameters termed δ_(H), δ_(P) and δ_(D), measuredin (cal/cm³)^(1/2), quantify the molecular cohesive forces (the hydrogenbonding, polar and dispersion forces) in a given compound or mixture ofcompounds. The so far commonly used membrane materials for protectivegarments have δ_(H) - and δ_(P) -values of about 3 or less, and δ_(D)-values of about 9. In view of the low δ_(H) - and δ_(P) -values, thesemembrane materials are designated as low-energy type polymers because ofthe relatively low level of intermolecular cohesive forces. Thesesolubility parameter values are fairly close to the solubility parametervalues occupied by a major part of the commonly used solvents and epoxymaterials.

It has now been found that polymer materials of the high-energy type,i.e. with solubility parameters considerably different from those so farcommonly used, exhibit superior properties with regard to beingimpermeable to chemical compounds, e.g. epoxy materials.

The invention relates to a protective garment comprising a membranecomprising a substantially water insoluble polymer material having asolubility parameter set (δ_(H), δ_(P), δ_(D)) which is positioned at asolubility parameter distance of at least 7 from the solubilityparameter set (δ_(H), δ_(P), δ_(D)) equal to (0,0,8).

DETAILED DESCRIPTION OF THE INVENTION

The distance A between the solubility parameter set of the chemical(δ_(HO), δ_(PO), δ_(DO)) and the solubility parameter set of the polymer(δ_(HM), δ_(PM), δ_(DM)) is defined as follows (cf. ref. 1 and 3):

    A=((δ.sub.HM -δ.sub.HO).sup.2 +(δ.sub.PM -δ.sub.PO).sup.2 +4(δ.sub.DM -δ.sub.DO).sup.2).sup.1/2

The parameter set of (0,0,8) is a suitable average representative of alarge number of hazardous chemicals encountered in the metal industry,the construction industry, and the chemical industry. While it cannot besaid that all hazardous chemicals contribute to this average (noteableexceptions are e.g. methanol and dimethyl sulfoxide), the hazardouschemicals which can be said for practical purposes to average at aparameter set of about (0,0,8) comprises by far the major number ofhazardous organic solvents and plasticizers, polymerization monomers,pesticides and detergents. One particularly important group of hazardouschemicals of which the parameter set of (0,0,8) is representative arethe above-mentioned epoxy materials. In this present context, the term"epoxy materials" designates two component types comprising a bindercomponent which contains epoxy monomer, dimer, or trimer, commonly basedon diglycidylether of bisphenol A, solvents such as ethylene, butanol,and butylacetat, and optionally pigments and fillers, and a hardenercomponent containing polyaminoamides and optionally aromatic amines oraliphatic polyamines.

In the known art, solubility parameter system is primarily used forformulating paint coatings, i.e., for selecting solvents for particularbinders. The principle is that a solvent is selected, the solubilityparameter of which is as close as possible to the solubility parameterof the binder. Often, a solvent is selected which is constituted by amixture of components, in which case the relevant solubility parameterset is the solubility parameter set of the mixture, which is calculatedfrom the parameter set of the individual components by calculating eachparameter in the set as the volume weighted average.

According to the present invention, the solubility parameter set,although calculated in the same manner, is used for a completelydifferent purpose, i.e., for predicting a completely differentcombination of relative properties between two materials, i.e., thebreakthrough time and the permeation rate of a fluid in a polymermembrane: It has been found that the greater the distance is between thesolubility parameter set of the fluid and the polymer, the longer is thebreakthrough time, and the lower is the permeation rate.

In practice, acceptable results with respect to increased breakthroughtime and reduced permeation rate are obtained when the distance betweenthe parameter set of (0,0,8) and the parameter set of the polymer,calculated as described above, is at least 7, preferably at least 9, inparticular at least 11, and most preferred around 13.

Materials which comply with these conditions are the so-calledhigh-energy polymer materials, i.e., polymer materials with highmolecular cohesive forces, in particular high hydrogen-bonding and polarcohesive forces, while most known polymer membrane materials, includingpolymer membrane materials conventionally used for protective garments,are low-energy polymer materials (which typically are at a distance of 6or lower from the solubility parameter set of (0,0,8).

The synthetic polymer high-energy material is one which is substantiallywater-insoluble. This term includes materials which will undergoswelling in contact with water, but is intended to exclude materialswhich are actually soluble in water. An example of a high-energymaterial which is soluble in water is polyvinyl alcohol. Althoughpolyvinyl alcohol shows a high breakthrough time and a low permeationrate for epoxy materials such as shown in the experimental section, andalthough polyvinyl alcohol has in fact been suggested as a membrane fora protective garment, vide German Offenlegungsschrift No. 2330316, thewater soluble character of PVA results in a number of disadvantageswhich are believed to exclude its utility as a protective garmentmembrane for practical purposes:

The water solubility of PVA renders it subject to dissolution in contactwith external aqueous media or in contact with sweat. Furthermore, evensmall amounts of water or moisture which will not directly dissolve aPVA membrane will tend to swell and plasticize the membrane to such anextent that it loses the permeation resistance properties it wouldotherwise possess in view of its position in the solubility parametersystem. Moreover, in the practical processing of PVA, where largeamounts of plasticizer must be used which will tend to increase themobility of the PVA molecules and hence to increase the permeability.

A particularly interesting class of polymer materials for the purpose ofthe present invention are copolymers substantially free of plasticizers,since the presence of plasticizers increases the mobility of the polymermolecules and hence increases the permeability.

An especially interesting class of polymer materials are copolymers of aC₂₋₅ alkene substituted with up to 4 hydroxy groups and a C₂₋₅ alkene,or homopolymers of a C₃₋₅ alkene substituted with up to 4 hydroxygroups. The C₂₋₅ alkene is preferably ethylene.

A particularly useful copolymer is a vinyl alcohol-ethylene copolymer.

In the following, the designation "PVAE" is used to designate a vinylalcohol-ethylene copolymer.

It is preferred that the vinyl alcohol-ethylene copolymer contains 40-80mole percent of vinyl alcohol and 20-60 mole percent of ethylene. Inparticular, it is preferred that the vinyl alcohol-ethylene copolymercontains 65-75 mole percent of vinyl alcohol and 25-35 mole percent ofethylene.

Vinyl alcohol-ethylene copolymers are described, inter alia, in DEAuslegeschrift No. 22339806, GB Patent No. 1212569, GB Patent No.1247114, and GB Patent No. 1489635. Vinyl alcohol-ethylene copolymerssuited for the purposes of the present invention are produced, e.g., byKuraray Company Limited, Osaka, Japan, and are available under the tradename "Kuraray EVAL". They are normally used as packing materials forfood; the main reason for their suitability for this purpose is theirresistance against permeation by oxygen and their capability of reducingthe loss of aromas from the food.

As appears from the experimental section, the PVAE materials show uniqueadvantages for the purpose of the present invention in that they showextremely long breakthrough time. In contrast to PVA, the PVAE materialsmay be produced and shaped into membranes without the use ofplasticizers, but with excellent flexibility and plyability. In additionto the advantage the the PVAE membranes have an extremely longbreakthrough time, they show the advantage of the main component inepoxy materials, DGBEA, does not wet PVAE materials, which is attributedto the fact that PVAE materials have a very high hydrogen bindingparameter δ_(H) compared to DGEBA. This is of major importance in thepractical use of the garments according to the invention and contributesto the high barrier effect of the PVAE materials because the contactarea between the membrane and the epoxy material is then essentiallyreduced.

According to particular embodiment of the invention, the substantiallywater insoluble high energy polymer material is laminated with a layerof another polymer. Several advantages may be obtainable by laminating alayer of the high energy synthetic polymer used according to the presentinvention with another polymer such as a polyolefin, in particularpolethylene or polypropylene:

PVAE materials exhibit some absorbtion of water. Water absorption in thePVAE material will to some extent reduce the barrier function of thePVAE membrane due to a certain plasticizing effect of the water. As aprotective garment is subject to the influence of water fromperspiration, an important type of laminate is one which comprises apolymer layer of a type which will reduce water permeation, such aspolyethylene or polypropylene, for application against the skin. Anotherpossibility is to laminate the other polymer to the outside of the highenergy polymer for protection against external water such as rain orspray.

Some chemicals, e.g. amines and alcohols, are able to permeate PVAErather easily, but are not capable of permeating polyethylene. Thus, alaminate comprising polyethylene and PVAE is an excellent barrieragainst both chemicals with high δ_(H), δ_(P) solubility parameters andchemicals with low δ_(H), δ_(P) parameters. PVAE/polyethylene laminates,therefore, provide a superior general protecting effect againsthazardous chemicals, including epoxy products. Also, a layer ofpolyethylene laminated with a PVAE membrane enhances the mechanicalproperties of the protective membrane and therefore constitute aneconomic construction in view of the relatively high cost of PVAEcompared to polyethylene.

In case of both prolonged wear of the garment or wearing at elevatedtemperatures as well under conditions subjecting the garment toinfluence from external water, it will be preferable that thesubstantially water-insoluble material having a solubility parameter setpositioned at solubility parameter distance of at least 7 from theparameter set (0,0,8) constitutes at least one intermediary layer of thelaminate, for instance being the central layer in a 3-layer laminate orbeing layers Nos. 2 and 4 in a 5-layer laminate.

In such a PE/PVAE/PE laminate, the PVAE layer is effectively protectedagainst water, amines, and alcohols. The PE/PVAE/PE laminate inpractical dimensions has excellent mechanical properties (flexibility,strength, and elongation).

The lamination may be performed by extrusion lamination in which thepolymer materials are extruded together into one membrane without anyaid to help the polymer materials adhere together. Extrusion laminationmay also be performed with the use of an adhesive promoter such as anorganometallic titanium compound, e.g., tetra-n-butyltitanate ortetra-i-propyltitanate. The lamination may also be aided by means ofoxidizing one of the polymers, e.g., oxidized polyethylene film asdescribed in Reference 6. Another method is lamination with an adhesive.In this method, the individual polymer films are laminated together bymeans of a thin layer (a few microns) of an adhesive such as a modifiedpolyoleofine, e.g. a modified polyethylene or a modified polypropylenesuch as the types manufactured by Mitsui Petrochemical Industry CompanyLtd., Japan, under the trade name ADMER™ or by the MitsubishiPetrochemical Company Ltd., Japan, under the trade name MODIC™. Otheruseful adhesives are acrylic resinous adhesives and modified vinylicresinous adhesives, the use of which is described in reference 7. Thismethod is especially useful if the polymers have such different cohesivecharacteristics that they do not adhere well to one another on theirown, e.g. in the case of a vinyl alcohol-ethylene copolymer andpolyethylene.

In order to avoid the possibility of pinholes in the high-energy polymerbarrier layer of the membrane, this layer should have a thickness of atleast 10 μm. In practice, the membrane will usually have a thickness inthe range from about 25 μm to about 5000 μm. For disposable garments,such as gloves, a preferred thickness range is 25-200 μm, in particular50-150 μm, especially about 100 μm. For garments for repeated use, apreferred thickness range is 300-1000 μm, especially 250-500 μm.

The protective garment of the invention may be a glove as mentioned ofthe disposable type, or of a type for repeated use, a hood forpretecting the face and head, a boot (both of the disposable type forcovering shoes and of the rubber boot type), a coverall suit (both ofthe type with integral gloves, boots, and hood, and of the type withseparate gloves, boots, or hood), or an apron.

For large garments subjected to mechanical influences such as coverallsuits with integral hood, gloves, and boots, it is preferable that thegarment is also laminated with a reinforcing layer, such as woven nylon.

When manufacturing garments or parts of garments the membrane materialmay be heat welded, cast (e.g. by immersion or dip-casting),pneumatically extruded, or sown (with subsequent covering of the seams).

Large suits or parts of suits may be lined with e.g. non-woven fibrousmaterial in order to increase mechanical strength and to increasecomfort.

The invention also relates to a method for the protection of mammalianskin against the influence of a chemical or mixture of chemicals, saidmethod showing the features set out in any of claims 23-27.

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a protective glove 1 according to the invention. Theglove is made from a polyethylene/vinyl alcohol-ethylenecopolymer/polyethylene laminate which, for illustration, is shown in asymbolic "delaminated" fashion. The glove may, e.g. be made from twosuperimposed layers of laminate by heat sealing along the contour of theglove and simultaneously cutting. If decided, the glove may thereafterbe turned inside out so that the seam is on the inside whereby dexterityis enhanced.

FIG. 2 shows a preferred laminate for a garment according to theinvention. Reference numeral 2 designates a polyolefine layer,preferably polyethylene or polypropylene, and reference numeral 4designates a layer of vinyl alcohol-ethylene copolymer or anothersuitable high-energy polymer material. Reference numeral 3 designates anoptional adhesive or adhesion promoter. Alternatively, the layers 2 and4 may be unified by, e.g., co-extrusion.

FIG. 3 illustrates another laminate for use in a garment according tothe invention. In FIG. 3, the numerals 5 and 9 designate the same ordifferent polyoleofines such as polyethylene or polypropylene, and 7designates a vinyl alcohol-ethylene copolymer. Reference numerals 6 and8 designate adhesive or adhesion promoter. Alternatively, the layers maybe unified by e.g., co-extrusion.

FIG. 4 illustrates the relation between the distance in solubilityparameter (A) and the time lag breakthrough time with respect toNeoprene (N, plots .sub.°) and PVC (P, plots •) respectively. Theindividual plots correspond to the following chemicals: C:Chlorobenzene, D: dimethylsulphoxide, H: n-hexane, M: methanol, T:toluene, Tr: trichloroethylene. The curves N and P represent the timelag breakthrough times as a function of the solubility parameterdistance between the polymer and the influencing chemical. It will benoted that at small distance, the time lag breakthrough time is lessthan 1000 seconds, whereas considerable improvements are obtained atdistances of 5 and above, in particular at distances at 7 and above. Inthe actual case illustrated in FIG. 4, the thickness of the PVC membranewas 0.7 mm as opposed to 0.5 mm for the Neoprene membrane. The fact thatthe PVC-curve is lower than the Neoprene curve in spite of the greaterthickness of the PVC-membrane reflects influence from the highproportion of plasticizer in the PVC-membrane.

FIG. 5 illustrates the manner in which the time lag breakthrough time iscalculated in the experimental section. The curve 36 shows theaccumulated concentration of the compound in question behind themembrane as the function of the time. At the beginning, the accumulatedconcentration is zero and remains zero until the first trace of compoundis detected at time T_(s). Thereafter, the accumulated concentrationincreases and becomes a linear function of time until an equilibrium isreached. The symbol θ designates the time lag breakthrough time. Thisbreakthrough time is determined from the extrapolations 38 and 40→42shown in the figure. T_(s) is determined at the actual detection limit.T_(s) is therefore different from material to material and fromexperimental setup to experimental setup which makes comparisons of themeasured results difficult. θ is dependent of the detection limit inquestion and is therefore, among other reasons, a better basis for acomparison of membranes.

FIG. 6 illustrates a test cell used in the experimental section formonitoring the permeation through membranes, an axially extendingcentral inlet bore 14 and, perpendicular thereon, an outlet bore 16. Ateach end, the central body is provided with screwed-on caps 18 and 20,respectively. The upper cap 18 secures two to oppositely arranged tefloncones 22 with central bore between which the membrane 24 to be tested isarranged. In the bores 14 and 16, bushings 26 and 28, respectively arearranged through which capillary tubes 30 and 32, respectively extend.

In operation, a sample 34 of a fluid chemical is arranged on top of themembrane 24. Through the capillary tube 30, a current of helium gas isdirected against the lower side of the membrane 24, from where the gas(together with any chemical which has permeated the membrane) isdischarged through the capillary tube 32 for analysis in a massspectrometer.

EXPERIMENTAL STUDIES

The breakthrough time of DGEBA in a series of low energy polymermaterials and some high energy polymer materials and laminates of lowenergy materials with high energy materials was determined. From thesedeterminations, the diffusion coefficient was determined by theso-called time lag method, the time lag diffusion coefficient D_(L)being expressed as ##EQU1## where I is the membrane thickness measuredin cm, and θ is the time lag breakthrough time in sec.

The basis of the time lag method is that the permeation rate of asubstance that is brought into contact with a membrane becomes constantwith time. This means that the concentration of the substance inquestion in a closed (detection) chamber on the desorption side, after acertain transition period, will become linearly increasing. Finally, inthe case when the air in the chamber is saturated or when all of thematerial has been absorbed, the concentration will remain constant, cf.the typical time lag curve in FIG. 5.

The measurements were performed with the aid of the test cell shown inFIG. 6, connected to a mass spectrometer. The instrumentation and thegeneral procedure in the performance of the measurements are describedin more detail in the literature (ref. 8).

The "outer" side of the membrane (absorption side) was covered withDGEBA (diglycidyl ether of bisphenol A). It was determined that themembrane was pinhole-free. The permeation of DGEBA was detected by massspectroscopic analysis with respect to DGEBA vapor on the "instrumentside" (desorption side) of the membrane. The permeation was determinedon the basis of the intensity of the signal at the mass numbers 77, 91and 94, the signal/noise ratio being best for these signals.

As the maximum measurement period, 240 min (4 hours) was chosen sincethis time interval corresponds to a working morning of uninterruptedcontact with epoxy products.

During the measurements, the test cell was thermostated at 40° C.

MATERIALS

The content of impurities of the DGEBA used was less than 1% accordingto liquid chromatography.

Permeability measurements were performed on 14 different membranes. Fourof these were specially produced. The others were made available asindustrial warehouse products or finished experimental products. Themembranes are specified in Table 1 and 1a. Membranes 1-10 were studiedin an introductory series of tests, Nos. 11-15 in a concluding series oftests.

RESULTS

The results of the measurements are summarized in Table 2 and 2a. Thetime point T_(s) for the first traces of DGEBA in the detection chamberwas measured directly. The detection limit was 1 picomole/sec. Theuncertainty of the breakthrough time θ is ±15%. The membranes studiedwere placed in the table according to increasing diffusion coefficient.

PVAE-1/PE was tested for permeability from both sides. After 335 min,the DGEBA had still not penetrated from the PE side. At the measurementafter 1217 min, the substance had penetrated.

All membranes were kept completely wetted with DGEBA during the tests.No membranes swelled to any directly visible degree with the substance.

                  TABLE 1                                                         ______________________________________                                        Specification of membranes studied                                                                       Thickness                                          Material no. and type      (mm)      Form                                     ______________________________________                                        1   Polyethylene (PE)      0.08      Film                                     2   Polychloroprene (neoprene, CR)                                                                       0.54      Plate                                    3   Silicone rubber (VSi)  1.16      Plate                                    4   Polyvinyl alcohol (PVA)                                                                              0.07      Film                                     5   Butyl rubber I (PIB, IIR)                                                                            0.22      Plate                                    6   Butyl rubber II (PIB, IIR)                                                                           0.48      Glove                                    7   Natural rubber (NR)    1.1       Plate                                    8   Polyisoprene (PIP)     1.1       Plate                                    9   Ethylene-propylene-terpolymer                                                                        0.9       Plate                                        (EPDM)                                                                    10  Chlorobutyl rubber/EPDM mixture                                                                      1.32      Plate                                    11  PE/PVAE-1/PE laminate (a)                                                                            0.056     Film                                     12  PVAE-1/PE laminate     0.095     Film                                     13  PVAE-1                 0.020     Film                                     14  PVAE-2                 0.016     Film                                     ______________________________________                                    

                  TABLE 1a                                                        ______________________________________                                        Specification of membranes studied                                            Material                                                                             Supplier:                                                              no.    Product brand                                                          ______________________________________                                        1      Allhabo, Sweden: Alloten LD                                            2      DuPont, USA:                                                           3      DuPont, USA:                                                           4      Kurashiki, Japan: Vinylon                                              5      Trelleborg, Sweden: 8700                                               6      Arsima, Arsima: 60951-3                                                7      Schonning & Arve, Denmark: AT-1                                        8      Schonning & Arve, Denmark: AT-2                                        9      Codan, Denmark: EPDM EJ-41*                                            10     Codan, Denmark: Cholorobutyl/EPDM CB-13/                               11     Kuraray Co. Ltd., Osaka, Japan: PE/EVAL-E/PE-                                 coextruded film                                                        12     Kuraray Co. Ltd., Osaka, Japan: EVAL-E/PE-                                    lami-film                                                              13     Kuraray Co. Ltd., Osaka, Japan: EVAL-E                                 14     Kuraray Co. Ltd., Osaka, Japan: EVAL-F                                 ______________________________________                                         (a) Threelayer laminate: polyethylene/vinyl                                   alcoholethylene-copolymer/polyethylene                                        *NR, PIP, EPDM and chlorobutyl rubber/EPDM plates (Nos. 7-10) were            especially produced for this study.                                      

                  TABLE 2                                                         ______________________________________                                        Membrane materials, time of first trace of DGEBA,                             breakthrough time, diffusion coefficient                                      and solubility parameters                                                                                         Break-                                                               First    through                                                    Membrane  trace of time for                                  DGEBA ("epoxymonomer")                                                                         thickness DGEBA,   DGEBA,                                    Membrane no. and materials                                                                     (mm)      T.sub.s (min)                                                                          δ (min)                             ______________________________________                                        4   Polyvinyl alcohol (PVA)                                                                        0.07      >240   >240                                    11  PE/PVAE-1/PE     0.056     >240   >240                                    12  PVAE-1/PE        0.095     >240   >240                                    13  PVAE-1           0.020     >240   >240                                    14  PVAE-2           0.016     >240   >240                                    1   Polyethylene (PE)                                                                              0.08      2.0    4.4                                     5   Butyl rubber I                                                                (PIB, IIR)       0.22      2.5    5.6                                     6   Butyl rubber II                                                               (PIB, IIR)       0.48      25     46                                      2   Polychloroprene                                                               (neoprene, CR)   0.54      16     38                                      10  Chlorobutyl/EPDM 1.32      11     75                                      7   Natural rubber (NR)                                                                            1.10      7.3    24                                      8   Polyisoprene (PIP)                                                                             1.10      6.5    24                                      9   Ethylenepropylen-ter-                                                         polymer (EPDM)   0.90      2.5    15                                      3   Silicone rubber (VSi)                                                                          1.16      7.5    19                                      ______________________________________                                    

                  TABLE 2a                                                        ______________________________________                                                                             Distance                                                                      between                                  Diffusion                            parameter                                coeffici-    Solubility parameters                                                                            Ref- set                                      Membrane                                                                             ent.      δ.sub.H                                                                         δ.sub.P                                                                      δ.sub.D                                                                       er-  DGEBA/                               no.    D.sub.L × 10.sup.8                                                                (cal/cm.sup.3).sup.1/2                                                                         ence material, A                            DGEBA  (cm.sup.2 /sec)                                                                         5.51    5.88 9.95  (3)  (cal/cm.sup.3).sup.1/2               ______________________________________                                        4      <0.057    13      7    8.5.sup.1  8.1.sup.4                            11     <0.036    10.5    6.5  8.5.sup.1  5.8.sup.4                            12     <0.104    10.5    6.5  8.5.sup.1  5.8                                  13     <0.005    10.5    6.5  8.5.sup.1  5.8                                  14     <0.003    10.5    6.5  8.5.sup.1  5.8                                  1       4        ˜0                                                                              ˜0                                                                           8.1   (10) 8.9                                  5      24        2.28    1.23 7.10   (3) 8.07                                        19                                7.8                                  6      14        1.6     1.1  7.8   (11) 7.58                                 2      21        1.3     1.5  9.5   (11) 6.2.sup.2                            10     65        --      --   --         --                                   7      140       3.5     1.0  9.0   (11) 5.6                                                                           5.6.sup.3                            8      140       -0.40   0.69 8.10   (3) 8.8                                  9      152       1.0     0.4  8.8   (11) 7.5                                  3      197       2.2     1.8  8.0   (11) 6.6                                  ______________________________________                                         .sup.1 The solubility parameters are, as far as is known, not established     for PVA and PVAE. The values stated are estimated.                            .sup.2 Secondary solubility range left out of consideration.                  .sup.3 The solubility parameters for PIP (synthetic natural rubber) were      determined with the aid of "raw elastomers" (ref. 3). The solubility          parameters for NR (natural rubber) were determined with respect to            vulcanized material. Since the membranes studied of both PIP and NR           consists of vulcanized material, it appears reasonable to use the             solubility parameters for NR in the distance calculations with respect to     both material types.                                                     

DISCUSSION

The membrane thicknesses are of the same order of magnitude as thosewhich occur in safety gloves. The measured breakthrough times θ andtrace times T_(s) therefore by themselvess give an impression of thesuitability of the material for safety gloves. Several membranes are ofessentially the same thickness, which enables direct comparison of θ andT_(s) within subgroups of the membrane materials in question. Wherethere are differences in the membrane thickness, the comparison shouldbe based on the calculated diffusion coefficient.

The breakthrough time θ varied within the group of all membranes studiedbetween 4.4 min (0.08 mm polyethylene (PE)) and more than 240 min (0.07mm polyvinyl alcohol (PVA), 0.056 mm PE/PVAE-1/PE and the like).

Disposable gloves manufactured from PE are, according to experience ofthe Labor Inspection's Administration of Worker Safety Regulations withEpoxy Products and Use of Them, quite common as a protection againstDGEBA and other constituents. In addition, gloves of polyvinyl chloride(PVC), nitrile rubber, neoprene or natural rubber are used. The resultsreported above demonstrate the clear superiority of the PVAE materialsover these known art materials.

Regarding laminates, one might fear that PVAE when laminated with PE,because of the "compulsory wetting" via PE, would have a shorterbreakthrough time than non-laminated PVAE. It was found that thebreakthrough time of DGEBA in contact with a PVAE/PE laminate was longerthan 240 min, regardless of whether DGEBA was brought into contact withthe PVAE or PE side of the laminate. The possible compulsory wettingeffect is therefore not of essential importance.

REFERENCES CITED

(1) Hansen, C. M. & Beerbower, A: Solubility parameters, p. 889-910 inKirk-Othmer: Encycl. Chem. Techn. Suppl. Vol., 2nd Ed., Wiley & Sons,New York 1971

(2) Hansen, C. M.: The three dimensional solubility parameter andsolvent diffusion coefficient, Their importance in surface coatingformulation, Danish Technical Press, Copenhagen 1967 (106 p.)

(3) Hansen, C. M.: Solubility in the coatings industry, Farg och Lack,17 (4), 69-77 (1971)

(4) Hansen, C. M.: "The universality of the solubility parameter", Ind.Eng. Chem. Prod. Res. Dev., 1969 (8: 1) 2-11.

(5) DE-Auslegeschrift 2339860

(6) GB Patent 1212569

(7) GB Patent 1247114

(8) Klaschka, F.: Physiologische Grundlagen des Hautschutzes,Arbeitsmed. Sozialmed. Praventivmed., 15 (1), 2-5 (1980)

(9) Linnarson, A. & Halvarson, K.: Studie av polymermaterialsgenomslapplighet for organiske foreningar (FOA-Rapport C-20414-H2),Forsvarets Forskningsanstalt, Stockholm 1981.

(10) Hansen, C. M.: The three dimensional solubility parameter--key topaint component affinities: I. Solvents, plasticizers, polymers, andresins, J. Paint. Techn., 39 (505), 104-117 (1967).

(11) Beerbower, A. & Dickey, J. R.: Advanced methods for predictingelastomer/fluids interactions, ASLE Transact., 12, 1-20 (1969).

(12) Kishimoto, A.: Gas barrier property and multilayer blown bottle,Jap. plast. age, 14 (152), 21-25 (1976).

(13) GB Patent 1489635.

I claim:
 1. A method for protecting skin against exposure to hazardous chemicals comprising positioning a protective garment adjacent to the skin, said protective garment comprising a substantially water insoluble polymer material, said polymer material being a copolymer of C₂₋₅ alkene substituted with up to four hydroxy groups and a C₂₋₅ alkene, or a homopolymer of a C₃₋₅ alkene substituted with up to four hydroxy groups.
 2. A method as claimed in claim 1, wherein said polymer is substantially free of plasticizers.
 3. A method as claimed in claim 1, wherein said C₂₋₅ alkene is ethylene.
 4. A method as claimed in claim 3, wherein said polymer material is a vinyl alcohol-ethylene copolymer.
 5. A method as claimed in claim 4, wherein said copolymer contains 40-80 mole percent vinyl alcohol and 20-60 mole percent ethylene.
 6. A method as claimed in claim 4, wherein said copolymer contains 65-75 mole percent vinyl alcohol and 25-35 mole percent ethylene.
 7. A method as claimed in claim 1, wherein said polymer material is laminated with a layer of another polymer.
 8. A method as claimed in claim 7, wherein said other polymer is a polyolefin.
 9. A method as claimed in claim 8, wherein said polyolefin is polyethylene.
 10. A method as claimed in claim 7, wherein said polymer material is an intermediate layer of a laminate.
 11. A method as claimed in claim 1, wherein said protective garment comprises a vinyl alcohol-ethylene copolymer layer laminated between polyethylene layers.
 12. A method as claimed in claim 1, wherein said protective garment has a thickness of about 25 um to about 5,000 um.
 13. A method as claimed in claim 12, wherein said thickness is from 25 to 200 um.
 14. A method as claimed in claim 12, wherein said thickness is from 50 to 150 um.
 15. A method as claimed in claim 12, wherein said thickness is about 100 um.
 16. A method as claimed in claim 12, wherein said thickness is 300 to 1,000 um.
 17. A method as claimed in claim 12, wherein said thickness is 250 to 500 um. 